You're talking about a 250ms delay to assure that actions are always done without desync aka lag position? Probably you will have to check the netcode compiled on the exe [I think it's that] and how it's done to be able to edit it to edit it to prevent that.I remember something related to Nog Algorithm [dunno the exact name, I just know that is something like that when you diff the exe] that would fix that but you will also get lag-position a ton of times as a consequence of using it so you should ask your players first about what they want - lag position or exact movements with a bit of delay like in the MOBA games.

According this, it's all about the version of the exe that you're using. Some users there also say that they have fixed that using a third party program at the topic.

Still, the best help that you can get related to this is going to eathena/rathena/hercules forums and ask for support related to it.